For years it has been common practice in strip treating plants to attempt to maintain the strip being treated centered on one or more of a series of rolls. To accomplish this end one or more steering rolls were provided in the treatment line to steer the strip material and maintain the centerline thereof as close as possible to a desired point on the rolls, normally the middle of the rolls.
Initially control for such steering rolls were mechanical and were manually operated, such as for example by manually turning a screw operated jack thereby adjusting the steering roll in some fashion.
It has become common practice to operate such steering rolls in an easier manner, such as by hydraulic controls, electric motors, and the like. These controls are most often triggered automatically by strip edge detectors which are located at one or both edges of the moving strip material. Each time a particular width strip is placed on a processing line whatever edge detectors were utilized to signal the control means had to be manually adjusted for the particular width of strip material.
Manual adjustment of edge detectors is quite undesirable. For example, in a typical strip anneal line one might find as many as six or more steering rolls. An operator would have to follow the leading edge of a particular width of strip material and reset each edge detector. When processing shorter strips, by the time such a strip reached the end of the processing line the operator would have to start all over again at the beginning. Should the operator forget to readjust for a different width strip, the edge detectors will continue to sense the edge as if it were the same width strip. In the case of a wider strip following a narrower one, the strip might well hang over an edge of the roll causing severe damage and down time.
It would thus be clearly desirable to economically provide a detector which automatically guides the center of a strip material over a particular point of the steering roll or rolls regardless of the width and length of strip material being processed. If the strip moves laterally during processing it can be brought back automatically on line.